How to prepare a mix session for stem mastering
Preparing a finished mixdown ready for ‘regular’ mastering is simple: make sure your track doesn’t peak above -2dB, export the track down to a stereo file, then send it to the mastering engineer. Easy!
However, prepping your mix session for stem mastering takes a bit more consideration. You’ll want to sum your collection of tracks down to a handful of stems that will facilitate the engineer’s job down the line, and as every mix has its own unique characteristics, it’s vital that you understand how to take full advantage of this approach.
The best way to do this is to create five or six group channels (ie, buses) in your DAW, route signals into them, then label them all up appropriately. These groups will then be your stems, and you can solo each in turn and export them. This will neaten up the final mix session, and ultimately will also allow you to keep track on your groupings.
Frequency balance must be considered when grouping track elements. If you bundle bright, fizzy synths with darker parts, it’ll be harder to brighten the latter sounds without introducing harshness. Instead, group and export sounds that sit in similar tonal regions.
If your mix contains auxiliary effect channels (delays, reverbs, etc), it’s a good idea to include these signals in with the original source sounds. To export these properly, solo your groups and render them out, to ensure said effects are baked into the source stems.
It makes a lot of sense to render your kick and bass down to two separate files. This will allow the mastering engineer to refine the balance of these two all-important low-frequency parts, then optimise their separation and interaction if required.